Electrical apparatus



Nov. 2, 1954 A. o. GROOMS 2,693,512

ELECTRICAL APPARATUS Filed April 6, 1950 5 Sheets-Sheet 1 Z i O INVENTOR.

Nov. 2, 1954 A. o. GROOMS ELECTRICAL APPARATUS Filed April 6, 1950 3 Sheets-Sheet 2 HIIIIIIIHIIIK Nov. 2, 1954 A. o. GROOMS 2,693,512

ELECTRICAL APPARATUS Filed April 6, 1950 3 Sheets-Sheet 5 9 Fl 8}, 0 INVENTOR.

United States Patent ELECTRICAL APPARATUS Albert 0. Grooms, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application April 6, 1950, Serial No. 154,246

9 Claims. (Cl. 200-83) This invention relates to electrical apparatus and more particularly to temperature controls used on refrigerators and other apparatus.

Briefly, my control includes an actuating means directly connected to the main control means which is in the form of a switch. A set of spring-loaded toggle blades are normally located in such a way and connected to the switch in such a way that at one end of the limited movement of the actuating means the toggle blades are exactly upon the dead center position. In one form of the invention a second control device, such as a switch, is made responsive to additional force and movement of the actuating means.

It is an object of my invention to provide an additional switch or control means which may be used as an alarm switch upon a control in which the actuating means is directly connected to the primary control device or switch.

It is another object of my invention to provide an improved adjusting system for a control in which the actuating means is directly connected to the control device.

It is another object of my invention to provide a simple adjustable mounting upon a support for a bellows or diaphragm having a coaxial thermostat tube means.

It is another object of my invention to provide a simple pressure-operated snap-acting switch means in which one of the points of actuation is made adjustable while the second point of actuation is kept substantially constant.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the invention is clearly shown.

In the drawings:

Fig. 1 is a vertical sectional view taken substantially along the line 11 of Figs. 3 and 4, showing a control and electrical circuit embodying one form of my invention shown in the alarm closed position;

Fig. 2 is a fragmentary view showing an alarm contact in the normal open position;

Fig. 3 is a sectional view taken substantially along the line 3-3 of Fig. 1;

gig. 4 is a top view of the control shown in Figs. 1 an Fig. 5 is a vertical sectional view of another form of control embodying my invention, taken along the line 55 of Fig. 8;

Fig. 6 is a fragmentary view showing the dead center location of the toggle blades at the opposite limit of travel from that shown in Fig. 5;

Fig. 7 is a fragmentary elevational view of the upper portion of the control shown in Fig. 5 including the alarm contact means and the electrical circuit;

Fig. 8 is a bottom view of the control shown in Fig. 5;

Fig. 9 is a vertical sectional view of another form of the invention taken substantially along the line 99 of Fig. 10; and

Fig. 10 is a sectional view taken substantially along the line 10-10 of Fig. 9.

Referring now to the drawings and more particularly to Fig. 1, there is shown a U-shaped metal frame between the upper end of which there is provided a terminal block 22 of electrical insulating material. The legs of the U-shaped frame 20 are fastened to the terminal block by screws 24. The terminal block 22 is provided with a terminal member 2'6 extending through and held by the block and having fastened to its inner end the curled end of a leaf spring 28. The free end of this leaf spring 28 is provided with a switch contact 31 adapted to make and break contact with a contact provided at the lower end of a second terminal member 32, which is threaded through the terminal block 22 so as to be adjustable in the axial direction. The leaf spring 28 is connected by an electrical insulating member 34 to the bellows follower 36 in the manner illustrated in Figs. 3 and 5. The bellows follower 36 is bonded to the closed free end of the flexible metal bellows 38.

The opposite open end of the bellows 38 has its rim sealed to an adjustable bellows mounting member 40. This adjustable bellows mounting member contains a capillary tube 42 which extends coaxially through it and enters the interior of the bellows 38 as shown in Fig. 3. The tube 42 is sealed by solder to the mounting member 40 and closed at its opposite end. It is charged with a suitable vapor. Beneath the bellows 38, the bellows mounting member 40 is provided with a knurled bearing portion which receives a split threaded sleeve member 44 tightly threaded within the flanged threaded opening 46 upon the bottom of the U-shaped frame member 20. The threaded member 44 is axially locked in place upon the bearing portion of the bellows mounting member 46 by a C-shaped washer 48 which is held in an annular groove provided upon the lower end of the mounting member 40. The capillary tube 42 is protected by a spring guard 50.

The opening and closing of the switch contact 31 is controlled by a set of toggle blades 52 and 54. One of the blades extends directly between the bellows follower and the adjacent side of the frame 20, while the other blade 52 extends from the bellows follower 36 to the upper end of a wide leaf main spring 56. The lower end of this leaf spring 56 is provided with a tongue 58 extending through a slot in the lower portion of the frame 20. For imposing a load upon the toggle blades 52 and 54 there is provided a hollow screw 60 which is threaded through a flanged aperture in the side of the frame 20 and engages the leaf spring 56 to deflect the spring 56 in order to place the column loading upon the toggle blades 52 and 54. The toggle blades 52 and 54 are provided with hardened chisel-shaped bearing ends which enter into notches provided for receiving these ends in the spring 56, the bellows follower 36 and the side of the frame 20.

Extending coaxially through the center of the screw 60 is a shaft 62 which at the remote end is supported within an aperture in the opposite side wall of the frame 20. The other end of this shaft 62 is provided with a knob 64 having a projection 66 thereon adapted to engage a projection 68 struck up from the thin sheet metal cover 70 so as to limit the rotation of the knob 64 and the shaft 62 to one revolution. The shaft 62 is provided with a splined portion upon which is mounted a cam 72 having its peripheral surface engaged by a projection 74 which is struck out from the leaf spring 56. A small coil spring 76 is provided beneath one of the shoulders of the leaf spring 56 and rests upon the bottom of the frame 20 to keep the projection 74 normally in engagement with the periphery of the cam 72. By this arrangement as the knob 64 is rotated the leaf spring 56 is raised or lowered by the engagement of the periphery of the cam 72 with the projection 74, so as to raise or lower the outer end of toggle blade 52 so as to adjust the dead center location of the toggle blades 52 and 54. This adjustment raises or lowers the temperature range of the controls. The screw 60 and the shaft 62 may be made independent so as to provide independent adjustment of the cam 72 and the screw 60; but, if desired, they may be locked together by solder or by a pin or set screw, so that they may be adjusted or rotated simultaneously. In this latter arrangement the tension of the spring 56 and the location of the toggle blades are adjusted simultaneously in a coordinated manner by the rotation of the knob 64.

The bellows follower 36 at its upper end is provided with two legs. The lower end of one leg is turned laterally to provide a projection 80 which engages the head of the adjustable differential screw 82 to limit the opening movement of the bellows follower 36. The other leg of the bellows follower 36 is turned laterally to provide a projection 84 which is adapted to engage the contact plunger 86 of a second switch mechanism which may 3 be used to control an alarm or warning device. The closing movement of the bellows follower is thereby yieldingly limited by this engagement of the projection 84 with the spring-pressed contact plunger 86.

This plunger 86 is made of an electrical insulating material and is provided with a flange 88 and a projection 90. A contact disc member 92 slips over the projection 90 and rests on top of the flange 88. It is held in place by a light compression coil spring 94 held at its lower end by the projection 90 and supported at its upper end by the projection 96 provided upon the lower end of the alarm adjusting screw 98. The screw 98 is held within a screw and nut assembly which includes an upper internally threaded member 121 of metal and a second member 123 of electrical insulating material to the lower end of which is fastened a third member 125 of metal which is threaded into the terminal member 22.

One electrical supply conductor 127 is connected to the terminal 26 with a branch connection to a gas-filled tube 129 which is also connected to the screw 131 threaded into the metal member 121. This screw 131 is also connected to an electrical resistance 133 which in turn connects to the other supply conductor 135. The appliance to be controlled, for example, an electrical refrigerator is represented by an electric motor 137 which is connected between the terminal 32 and the supply conductor 135.

The parts are so designed that the toggle blades 52 and 54 are straight when the projection 84 rests normally on the contact plunger 86 with the alarm contact 92 out of engagement with the threaded member 125, and with the switch contact 31 in normal contact engagement with the terminal 32. The switch terminal 32 is in this position adjusted to give proper electrical contact pressure between it and the contact 31. differential screw 82, which is accessible from the upper side of the terminal block 22, as shown in Fig. 4, then is adjusted so that its head is moved a sutficient distance away from the projection 80 to provide the desired amount of opening movement of the switch contact 31. The capillary tube member 42 is then cooled to the desired switch opening temperature and the nut 44 is adjusted until the switch opens. Before this adjustment is made, the toggle blades 52 and 54 will be in a straight line so that this switch opening adjustment is not affected by the tension of the spring 56. The temperature of the capillary tube 42 is then changed to the temperature at which it is desired that the switch contacts should close. The screw 60 is then adjusted until the switch contact 31 moves to the closed position.

The capillary tube 42 is then raised to the temperature at which it is desired an alarm or warning be indicated. In the circuit previously described, the gas filled tube 129 is energized as long as the system is in an electrical condition to operate properly. If there should be a power failure or if the temperature should reach the alarm temperature, the tube or bulb 129 will be deenergized thereby giving a warning of the failure to function properly. In the case of a refrigerator, it will indicate that there is danger that the refrigerator will not provide proper refrigeration. The screw 98 is adjusted to vary the tension of the spring 94 so that when the capillary tube 42 is at the desired alarm temperature, the alarm contact 92 just makes contact with the threaded metal member 125 so that through its electrical connection in the form of a connector 139 with the terminal 26, a shunt is closed around the gas-filled tube 129 so that it will go out. In this way the opening and the closing, and the alarm functions are set independently of each other.

For a freezer, for example, the nut 44 may be adjusted to open the switch contact 31 at plus 4 F. The screw 60 may be moved until the switch closes at plus 16 F. The alarm screw 98 may be adjusted so that the alarm will close at 21 /2 F. If the screw 60 is locked to the shaft 62 by solder or other suitable means, a rotation of the knob 64 to another position will cause the contact 31 to open at minus 6 F. and to close at plus 7 F. while the alarm contact 92 will close at l2.5 F. If the knob 64 is turned to the extreme cold position, the switch contact 31 will open at minus F. and close at minus 3 F., while the alarm contact 92 will close at plus 8 F.

In normal operation to the switch closing position, the projection 84 lightly engages the plunger 86. Since the moving parts are light in weight and move only a very short distance. there is only a small inertia force and the The- . v 4 plunger 86 is depressed only slightly. When there is an abnormal increase in the temperature of the capillary tube 42 resulting in an abnormal increase in the pressure within the bellows 38, the bellows 38 will expand further and will move the bellows follower 36 beyond the normal stopping point. This overtravel will be opposed by the tension of the coil spring 94 and the leaf spring 28. When the temperature and resulting pressure have risen sufliciently, the plunger 86 and two springs 94 and 28 will be deflected sufliciently to cause the contact disc 92 to engage the threaded member to close the shunt circuit through the connector 139 to shunt out and thus extinguish the lamp 129 to give a warning of the abnormal conditions.

If it is desired to use this control for a water cooler, the cam 72 is omitted and the nut 44 is adjusted to provide a contact opening temperature of 33 or 34 F. The closing temperature may be adjusted by the knob 64 which will turn the screw 60 so as to give the desired average water temperature.

The form shown in Figs. 5 to 8 inclusive is intended for water coolers, milk coolers and wet bottle coolers. It provides a very narrow differential with a limited range adjustment. It is identical to the form shown in Figs. 1 to 4 with the following exceptions: The control knob 264 connects directly to a shaft 262 extending coaxially through the separately adjustable screw 260 preferably provided with a hexagonal head. The shaft 262 omits the cam 72 and its splined mounting and in its place in Fig. 5 there is fixed to the outer end of the shaft a spur pinion 272. To prevent the free rotation of the shaft 262 there is provided within the modified frame 220 a *Belleville type washer 261 held in place by a collar 263. The pinion 272 meshes directly with a spur gear 271 provided with an integral hub 273 fitted and rotatable within an aperture in the modified frame member 220. The chisel-shaped end of the adjacent toggle blade 54 is held by the inner end of a hexagonal headed pin 253 which extends through the spur pinion 271 and is held in place by a spring retaining washer 255. The aperture through which the pin 253 extends is eccentrically located a small amount relative to thehub portion 273 of the spur pinion 271 so that when the knob 264 and the shaft 262, and the pinion 272 are rotated the pin 253 is moved a small amount upwardly or downwardly to provide a limited range adjustment.

The leaf main spring 256 omits the projection 74 and the spring 76 is also omitted. The cotterpin 275 extends through the tongue 258 at the lower end of the spring 256 to hold it locked in place to prevent longitudinal movement. In this form I prefer to use an adjustment screw 282 having a large head similar to the screw 82, but 1n addition this screw has a second flange 283 which stops the movement of the bellows follower member 36 in the switch closing direction. The amount of movement of the bellows follower istherefore limited in both directions by the screw 282 and the length of this movement is fixed, although the location thereof may be ad justed by the rotation of the screw 282. 1

In this form the capillary tube is first cooled to the cut on temperature and then the split screw 44 is adusted until the switch snaps to closing position. As shown in Fig. 8 there are markings 243 provided upon the bottom of the frame 220. Similar markings (not shown) are provided upon the frame 20 shown in Figs. 1, 2 and 4 lnclusive. A rotation of the screw 44 through an angle equal to that of one of the marks 243 to another mark a change of substantially 1 degree in the switch closing or cut-on temperature. The slot in the screw 44 may be used as an indicator in connection with the marks 243. After the switch closing temperature is set the capillary tube 42 is cooled to the switch opening temperature and the screw 260 is adjusted until the switch opens. As shown in Fig. 6 the toggle blades 52 and 54 are substantially straight in the open circuit positron of the switch so that the spring force of the main leaf spring 256 does not affect the switch closing temperature and pressure.

As shown in Fig. 7 this modification may be used wlth the alarmpontact mechanism in a manner similar to that shown in Fig. 1. However, when this form is used with the alarm contact mechanism the adjusting screw 282 1s replaced by the adjusting screw 82 which omits the flange 283. By omitting the flange 283 the bellows follower 36 is allowed an amount of'overtravel suflicient to move theplunger 86 until:'the alarm contact one 92 engagesth'e' threaded" metal "member 125 to close' the'alarmshunt'circuityasdescribed inntore' detail in connectionwithFigs; '1 to 4.

In" Figs? 9--and"lO"there is shown a form-of"'control which is particularly intended to operate upon a defrosting cycle and in other applications wherein it is desired that the switch closing shall take place at all times at the same temperature regardless of the adjustment of the control. For example, this control may be set to close at all times at a temperature of 33 F. or 34 F. to insure that any frost will be melted from the evaporator before the refrigeration cycle is resumed. However, the switch opening temperature may be made variable so that the refrigeration cycle may be continued until a lower temperature is reached to provide more refrigeration when required. This control is identical to the control shown in Fig. 1 with the following exceptions: The shaft 462 upon which the knob 464 is mounted has no function except to support the knob 464, and to provide a connection connecting the knob 464 to the screw 460 which is exactly like the screw 60 shown in Fig. 1. This screw 460 is soldered to the shaft 462 so that it rotates with the knob 464 to adjust the spring force of the leaf main spring 456 which, as in the form of Fig. 5, is locked in place by a cotterpin 475 extending through tongue 458. As in the form shown in Figs. 5 to 8, the cam 72 and the projection 74 are omitted. The toggle blades 52 and 54 are arranged to be straight across when the bellows follower 36 is in the switch open position with its projection 80 in contact with the head of the screw 82. This control is shown provided with an alarm switch mechanism similar to Figs. 1 to 4 which serve the same function.

To set the switch, the screw 282 is turned until the toggle blades 52 and 54 are straight across when the bellows follower 36 is in the switch open position. The capillary tube 42 is cooled to the desired cut-on temperature such as 33 F. or 34 F., and the screw 44 is then adjusted until the bellows follower 36 moves the switch to closed position. The capillary tube 42 is then cooled further to the desired cut-ofi' temperature and the screw 460 is then adjusted until the switch opens. In this position of adjustment the screw 460 is soldered to the shaft 462 with the knob 464 in the desired position for this particular cut-off temperature to lock the screw in this adjusted position relative to the knob 464. If it is desired to omit the alarm switch mechanism the screw 82 may be replaced by the screw 282.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims.

What is claimed is as follows:

1. A control arrangement including a support means, a control means and an actuating means operably connected together and mounted upon the support means, a toggle means acting upon the actuating means for controlling the operation of the control means for holding the control means in first and second control positions, said toggle means including a spring means, an adjustable stop means cooperating with the toggle means and the control means to stop the movement of the control means at said first and second control positions with said toggle means in predetermined positions, and means for adjusting said spring means without affecting the predetermined positions of said toggle means.

2. A control arrangement including a support means, a control means and an actuating means operably connected together and mounted upon the support means,

a toggle means acting upon the actuating means for controlling the operation of the control means for holding the control means in first and second control positions, said toggle means including a spring means, an adjustable stop means cooperating with the toggle means and the control means to stop the movement of the control means at said first and second control positions with said toggle means substantially in the dead center position in one of said control positions, and means for adjusting said spring means without changing the stopping positions of the control means and the toggle means.

3. A control arrangement including a support means, a control means and an actuating means operably connected together and mounted upon the support means, a toggle means acting upon the actuating means for controlling the operation of the control means for holding "means at "s'aid'"first"and *second control positions with said-toggle means substantially 'inthe dead center position in one of said control positions, and means for varying the tension of said spring means while retaining said dead center stopping position of the toggle means.

4. A control arrangement including a diaphragm means, a control means, a connecting means extending between the diaphragm means and the control means to provide a movement of the control means in proportion to the movement of the diaphragm means, a toggle means connected to one of said means for controlling the movement of said one means, a flexible stop means for said one means, said flexible stop means being provided with switch means operable from one position to another upon a predetermined deflection of said stop means.

5. A control arrangement including a diaphragm means, a control means, a connecting means extending between the diaphragm means and the control means to provide a movement of the control means in proportion to the movement of the diaphragm means, a toggle means connected to one of said means for controlling the movement of said one means, a flexible stop means for said one means, said flexible stop means being provided with switch means operable from one position to another upon a predetermined deflection of said stop means, and an adjustment means for varying the location of said diaphragm means relative to said control means and said flexible stop means.

6. A control arrangement including a support means, a control means and a fluid motor actuating means mounted upon said support means, proportionate movement connecting means operably connecting said control means and said actuating means to provide proportionate movement, a toggle means acting upon said actuating means for controlling the operation of the control means, toggle snap producing spring means acting upon one portion of said toggle means to form a toggle snap action means, a first independent adjusting means for said toggle snap producing spring means, and a second independent adjusting means for shifting the dead center position of the toggle means.

7. A control arrangement including a diaphragm means, a control means, a connecting means extending between the diaphragm means and the control means to provide a movement of the control means in proportion to the movement of the diaphragm means, a toggle means connected to said connecting means for controlling the movement of the connecting means, a flexible stop means for said connecting means, said flexible stop means being provided with switch means operable from one position to another upon a predetermined deflection of said stop means.

8. A control arrangement including a diaphragm means, a control means, a connecting means extending between the diaphragm means and the control means to provide a movement of the control means in proportion to the movement of the diaphragm means, a toggle means connected to said connecting means for controlling the movement of the connecting means, a flexible stop means for said connecting means, said flexible stop means being provided with switch means operable from one position to another upon a predetermined deflection of said stop means, and an adjustment means for varying the flexibility of said flexible stop means.

9. A control arrangement including a support means, a control means and an actuating means operably connected together and mounted upon the support means, a toggle means acting upon the actuating means for controlling the operation of the control means for holding the control means in first and second control positions, said toggle means including a spring means, an adjustable stop means cooperating with the toggle means and the control means to stop the movement of the control means at said first and second control positions with said toggle means in predetermined positions, means for adjusting said spring means without affecting the predetermined positions of said toggle means, and means for adjusting the location of the toggle means without affecting the adjustment of said spring means.

(References on following page) References Cited in the file of this patent Number UNITED STATES PATENTS Name Date Long June 26, 1917 5 Spencer Aug. 6, 1935 Number 

